1. Field of the Invention
This invention relates generally to improvements to a coupling assembly which includes one coupling half which comprises a joint body for a relatively thin hose having a diameter of about 20 mm or less and the other coupling half which comprises, for example, a tubular coupling end member or a metal tube for another hose having an outer diameter of 20 mm or less to provide a supply passage through which oil or air is supplied to automobiles, various machines, equipment or the like.
2. Description of the Prior Art
Conventionally, for example as shown in FIG. 5, a coupling assembly of this type includes a joint body 21 which has an axial fluid bore 24 extending therethrough, a tubular protrusion 23 provided at one end and to be connected to a hose and an internally threaded hole 22 provided at the other end and having a large diameter. The joint body has a truncated conical seat 25 in the hole. The assembly also includes a flare type coupling end provided at one end of a metal tube P' and seated on the truncated conical seat, and a nut 26 turned into the internally threaded hole 22 to tighten the flare against the seat for coupling purposes.
However, this assembly requires a large push force to cause a face-to-face contact between the seat 25 and the flare, may bring about an uneven contact between the seat and the flare due to uneven worked surface of the flare, and has no function to align the seat and the flare. The mechanical strength of the flare will be degraded due to thinning, deformation and twisting of the flare caused by large push force applied to the flare and excessive uneven tightening of the flare. Thus, vibrations of an engine, a machine, equipment or the like concerned may easily cause cracks or breakage in the neck of the flare to thereby cause leakage of air or oil. Tightening the nut, especially by the use of a coupling tool in a narrow space, is troublesome.